Sporting magnificent quiffs that speak of hours in front of the mirror, three handsome lads swagger around, eyeing up the young women. Harassed dads try to keep their daughters in line, but one lad manages to hook up with a girl. Dad looks on and flashes a menacing smile. The youth covers his snigger with an anxious hand.

This, as David Attenborough explained in Natural World: Clever Monkeys (BBC2), was a display of Machiavellian intelligence: the concealment signals an apology to the dad, which is an example of using your brain to control society. And, when it comes to that, Peter Mandelson has nothing on the gelada monkeys of Ethiopia's Semien Mountains.

I know what I'll do, the deviously manipulative Daddy Gelada thought: I'll grab a helpless baby, plonk him on my back and then that poser in the quiff will never dare attack me. But kids are an amoral lot these days, and the dashing young blade set upon Daddy anyway, mauling baby and ruffling quiff.

Some monkeys, it turned out, possess grammar (once thought uniquely human), as well as an ability to think and talk about things beyond their immediate experience. Inevitably, this intelligence turned out to be Machiavellian, too: a weedy white-faced capuchin shouted "snake" (in monkey talk) when there was none, in order to scare off his rivals and steal their food.

The story of how monkeys had learned to farm and go to war with each other seemed to mirror our own evolution - although that may have been because Attenborough had been given a big red dial labelled "monkey/man comparison overdrive" which he kept ramping up to 11. It left me wanting to go back 40m years, to the days when we might have been pygmy marmosets happily farming sap from trees in South America. But I suppose there is always the danger we would instead find ourselves among the noisy troops of baboons and geladas, who had quit the forests for the plains.

These more complex societies required greater intelligence, said Attenborough, but brightness did not bring happiness. Low-ranking baboons suffered ulcers and high blood pressure; when deposed, once high-ranking baboons showed signs of depression. When our ancestors left the trees, said Sir David, they changed, too, becoming more predatory and dangerous than the apes and monkeys they left behind. "Becoming clever," he said, "can mean being controlling, stressed, perhaps unhappy." Forget brains: surely the recipe for unhappiness is wrestling with your unruly quiff in the reflection at the waterhole every morning.

Machiavelli reappeared in True Stories: Mr Untouchable (More4), a documentary about Leroy "Nicky" Barnes, who credited the sly Italian with transforming him from a hopeless drug addict to the self-styled king of the 1970s Harlem heroin trade. "Machiavelli, very devious character," explained Barnes's sad-eyed former right-hand man Joseph "Jazz" Hayden, helpfully.

A familiar cast of grizzled ex-gangsters and braces-popping feds talking over a predictable soundtrack of Curtis Mayfield's Pusherman and Superfly gave this long programme a stereotypical and superficial start. It took a while before it dawned on me that the chunky gold signet ring belonging to some big-talking bloke we never actually saw was not a hideously cliched dramatic re-enactment but Barnes himself.

Living a new life under a witness protection programme, he agreed to be filmed in the shadows, surrounded by money and cigars, spouting boastful guff such as: "If you're in powder, you've got to be vicious." He wasn't apologising for flooding black neighbourhoods with heroin, cheating on his wife (who in the glory days was said to have "a black belt in shopping"), or "ratting" on his old mates when he was inside. As he put it, "If you're going to say, 'Fuck the King', then the King is gonna sing."

The film refrained from directly judging Barnes, but moral clarity was found in the fuzzy voice of his former associate Frank James, interviewed on the phone from prison. While Barnes gloated about being free when his former mates who "fucketh" with him were still doing time, James hoped Barnes would use the documentary to spread the word to young people that crime did not pay. Barnes did not.

James was also the very first voice you heard, on the hotline from where he has been incarcerated for 24 years, reflecting on the fetishisation of Barnes: his fictionalised appearance in American Gangster, the rappers who still pay him homage, and the contradictions of this documentary. "Nick needs this to survive. He needs the notoriety. The only thing we're really doing, we're giving him a transfusion. We're resurrecting him."